1. Field of the Invention
The present invention relates to semiconductor fabrication techniques, and in particularly to a method for forming an opening in a semiconductor device.
2. Description of the Related Art
With the rapid development of integrated circuit fabrication technologies, device miniaturization and integration is an important trend and topic in the electronics industry.
For the conventional method of forming an opening in a semiconductor device, a semiconductor substrate is provided and then a dielectric layer is formed over the semiconductor substrate. Thereafter, a photoresist layer is formed over the dielectric layer. After that, a conventional photolithographic process is used to define and form a patterned photoresist layer. Afterwards, using the patterned photoresist layer as an etching mask, an etching operation is carried out to remove a portion of the dielectric layer exposed by the patterned photoresist layer, thereby leaving a patterned dielectric layer with openings exposing a portion of a surface of the semiconductor substrate. The openings formed in the patterned dielectric layers may function as contact holes or contact vias, and conductive materials may sequentially fill the openings to form conductive contacts or vias therein.
In the aforementioned method of forming an opening in a semiconductor device, however, there are problems which need to be resolved. For example, the critical dimension (CD) of the opening formed in the photoresist layer being transferred to the opening formed in the dielectric layer may be inaccurate since a sloped sidewall profile of the opening is typically formed in the photoresist layer such that a critical dimension (CD) of the opening formed in the dielectric layer is different from the critical dimension (CD) of the opening formed in the photoresist layer. Ultimately, functionality of an element such as conductive contacts formed in the dielectric layer is affected and the reliability and yield of the semiconductor device comprising the same is also affected.